It can be advantageous to operate two buck converters in multi-phase configuration. When run at the same frequency and with opposite phase, the resulting output current ripple is significantly reduced. The input current ripple may also be significantly reduced.
Hysteretic power converters are widely used for Solid State Lighting (SSL) applications, for example in cars. Many SSL applications require a low current ripple. However, hysteretic converters have no defined frequency and therefore are not used in multi-phase configurations. Instead, large filter capacitors are used to achieve a low ripple current. In LED matrix applications, the output voltage changes frequently with the number of shorted LEDs, causing the switching frequency of the hysteretic converter to vary frequently and over a wide range. This makes filtering more complicated and expensive.
Throughout this disclosure, the term ‘hysteretic power converter’ includes both power converters with real hysteresis and power converters with artificial hysteresis. An example of a hysteretic power converter with artificial hysteresis is the median converter which used controlled time delays to emulate hysteresis.